Python 括号和范围内的变量

Question

([i]+[0]*n)是什么意思，为什么括号里是i和0？？

previous, current = current, [i]+[0]*n

为什么我不能在下一行打印当前值？像这样：

previous, current = current, [i]+[0]*n
print(current)

我有一个错误：TabError：缩进中制表符和空格的使用不一致

#!/usr/bin/env python

# This is a straightforward implementation of a well-known algorithm, and thus
# probably shouldn't be covered by copyright to begin with. But in case it is,
# the author (Magnus Lie Hetland) has, to the extent possible under law,
# dedicated all copyright and related and neighboring rights to this software
# to the public domain worldwide, by distributing it under the CC0 license,
# version 1.0. This software is distributed without any warranty. For more
# information, see <http://creativecommons.org/publicdomain/zero/1.0>


def levenshtein(a,b):
    "Calculates the Levenshtein distance between a and b."
    n, m = len(a), len(b)
    if n > m:
        # Make sure n <= m, to use O(min(n,m)) space
        a,b = b,a
        n,m = m,n

    current = range(n+1)
    for i in range(1,m+1):
        previous, current = current, [i]+[0]*n
        for j in range(1,n+1):
            add, delete = previous[j]+1, current[j-1]+1
            change = previous[j-1]
            if a[j-1] != b[i-1]:
                change = change + 1
            current[j] = min(add, delete, change)

    return current[n]

if __name__=="__main__":
    from sys import argv
    print(levenshtein(argv[1],argv[2]))

Answer 1

出现以下错误

TabError: inconsistent use of tabs and spaces in indentation

只是缩进不正确。所以，使用文本编辑器检查缩进是否正确。

即将

previous, current = current, [i]+[0]*n

在给定代码的下面的for循环中

for i in range(1,m+1):
        previous, current = current, [i]+[0]*n

所以，i 是索引（或计数器变量），他正在做的是制作一个列表，该列表将第一个元素作为索引，然后是 n 个零。这里 n 是在以下代码中计算的第一个字符串的长度

n, m = len(a), len(b)

所以，例如，如果 n = 10 且 i = 1，则 [i] + [0]*n 将是

[1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

所以，他只是想列一个清单，如上所示

Python 括号和范围内的变量

Python variable in brackets and range

python

levenshtein-distance